The invention relates to a process for the continuous introduction of fine grain solids including dust-like solids into a reaction space which is under pressure. The invention is particularly of interest for the introduction of finely divided coal into a gasifier under pressure such as concurrent flow or fluidizing bed gasifiers.
It will be understood, however, that the process of the invention can also be used for the introduction of solids into reaction spaces where other chemical, physical and/or metallurgical reactions are involved.
It has already been proposed to mix finely divided and even dust-like coal with a suitable liquid, preferably water in order to introduce the coal into the gasifier where it is subjected to gasification under pressure. The necessary pressure of the mixture of coal and liquid such as water is obtained, for instance by pump action. In the heating zone a steam-coal dispersion is then formed from the mash of coal and liquid and this involves a further pulverization of the coal. The dispersion is then passed into the pressure gasifier.
A flow diagram of this process which is known under the name "Texaco Process" will be found, for instance, in the publication "Chemie-Ingenieur-Technik", 46 (1974), page 949, FIG. 7.
In this prior art process the vaporous flow medium is passed into the pressure gasifier more or less united with the coal dust. It therefore takes part in the subsequent reaction such as partial oxidation. This, in many cases, leads to undesirable results, for instance because of a high proportion of water vapor in the reaction mixture.
It is therefore an object of the invention to provide for a process for the continuous introduction of fine-grained, including dust-like, solids into a reaction space which is under pressure in which process the conveyor or flow medium does not take part in the subsequent reaction but can be recirculated for further use. It is an object also thus to lower the necessary energy. Another object of the invention is to provide for a flow medium which is not toxic and not explosive.